JP3374957B2 - DC-AC power converter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-AC that supplies a single-phase AC voltage of arbitrary amplitude and frequency to a load or regenerates DC power to a single-phase AC power supply by a DC-AC conversion operation of an inverter. The present invention relates to a power converter.

[0002]

2. Description of the Related Art FIG. 10 conceptually shows a conventional DC-AC power converter, in which 100 is a DC power supply and 20 is a DC power supply.
0 is a DC-DC converter such as a step-up chopper, 300 is a smoothing capacitor, 400 is a single-phase voltage source inverter, 50
Reference numeral 0 is a single-phase circuit such as a single-phase AC motor as a load.
In this conventional technique, the DC power supply 100 and the converter 200 are used.
By transmitting and receiving DC power to and from the DC voltage, the DC voltage across the smoothing capacitor 300 is maintained at a predetermined value, and an inverter 400 using this DC voltage as an input voltage generates a single-phase AC voltage having a predetermined amplitude and frequency. It is generated and supplied to the single-phase circuit 500.

Next, FIG. 11 is a circuit diagram showing a specific example of the prior art of FIG. In FIG. 11, 101 is a DC power supply, 102 is a reactor, 201 is a step-up chopper for boosting the voltage of the DC power supply 101 to a predetermined DC voltage, 301
Is a smoothing capacitor, 401 is a single-phase voltage inverter that supplies a single-phase AC voltage to the single-phase load 501 (single-phase voltage type PW
M inverter), D is a diode, and Tr1 to Tr5 are self-extinguishing type semiconductor switching elements such as IGBTs to which antiparallel diodes are respectively connected.

In the above structure, the boost chopper 201
Stores energy in the reactor 102 by short-circuiting the DC power supply voltage via the reactor 102 by the switching element Tr5. Then, by turning off the switching element Tr5, the energy accumulated in the reactor 102 is supplied to the smoothing capacitor 301 together with the energy of the DC power supply 101. As a result, the voltage of the smoothing capacitor 301 becomes a DC voltage higher than the DC power supply voltage.

On the other hand, since the operation of the single-phase voltage source inverter 401 is well known, its explanation will be omitted, but two switching patterns for controlling the output voltage by controlling the conduction states of the four arms, It is possible to select two switching patterns, so-called zero voltage vectors, in which the output voltage becomes zero by making all the upper arms or the lower arms conductive. By setting the capacity of the smoothing capacitor 301 to be sufficiently large, it is possible to independently switch the boost chopper 201 and the inverter 401 independently.

FIG. 12 is a circuit diagram showing another specific example of the prior art shown in FIG. In this conventional technique, the AC power output from the inverter 401 is regenerated to the single-phase AC power supply 502 via the reactor 503. In this conventional technique, the input side DC voltage of the inverter 401 needs to be larger than the maximum value of the power supply voltage of the single-phase AC power supply 502, which is the regeneration destination, and when the DC power supply voltage is smaller than this, the boost chopper is used. It is necessary to use 201 to boost the voltage by the same operation as in FIG.

[0007]

In the prior art of FIG. 10, converter 200 must have a semiconductor switching element in order to keep the input side DC voltage of inverter 400 at a predetermined value, and the circuit configuration is correspondingly increased. It becomes a cause of increasing the complexity and size of the device. More specifically, in the prior art shown in FIGS. 11 and 12, which are the specific examples of FIG. 10, all of the apparatus require five self-extinguishing type semiconductor switching elements. If the control circuit and the like are included, the circuit configuration becomes complicated and expensive. Moreover, since the responsibility of the step-up chopper 201 for the semiconductor switching element is great, it has been a cause of hindering the downsizing of the device.

Therefore, the present invention intends to provide a DC-AC power converter which reduces the number of semiconductor switching elements in the entire device, simplifies the circuit configuration, downsizes the device, and reduces the cost. It is what

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 is a single-phase voltage type inverter which performs DC-AC power conversion by operation of a semiconductor switching element and outputs a single-phase AC voltage. , A smoothing capacitor connected between the DC input terminals of this inverter, a single-phase circuit such as a single-phase load or single-phase AC power supply connected between the AC output terminals of the inverter, and a series connection between the AC output terminals of the inverter. It is provided with a diode group consisting of a plurality of diodes which are connected and whose polarity is inverted in the middle of the mutual connection point, and a DC power supply connected between the polarity inversion point inside the diode group and one end of the smoothing capacitor. ing. Then, alternating-current power is supplied to the single-phase circuit by the switching operation of the semiconductor switching element forming the inverter. In addition, a zero voltage vector is output according to a specific switching pattern of the inverter, and DC power is exchanged with the DC power supply via the diode group.

FIG. 1 is a conceptual diagram of the invention described in claim 1. In the figure, similarly to the above, 100 is a DC power supply, 300 is a smoothing capacitor, 400 is a single-phase voltage-type inverter, and 500 is a single-phase AC motor that exchanges AC power with the inverter 400, a transformer, or a single inductor via an inductance. It is a single-phase circuit such as a phase AC power supply. Furthermore,
A diode group 600 is formed by connecting a plurality of diodes in series so that the polarities are inverted at internal connection points. Both ends of the diode group 600 are connected to the inverter 400.
, And the polarity reversal point (virtual neutral point) inside the diode group 600 is connected to the positive electrode of the DC power supply 100. The negative electrode of the DC power supply 100 is connected to the connection point between the lower arm of the inverter 400 and the smoothing capacitor 300, and the inverter 400, the diode group 600, and the DC power supply 100 have the same voltage and current as the DC power supply 100. When viewed through the diode group 600 from the AC output terminal, the components are connected in a loop so as to have a zero phase component (a component having the same magnitude and having no phase difference).

In the above structure, AC power is transferred between the inverter 400 and the single-phase circuit 500 by the inverter 4
The control is performed in the same manner as in the past by controlling the electric power by the line voltage of 00 and the current (load current) flowing between the lines. That is,
When the single-phase circuit 500 is a single-phase load such as an AC motor, AC power is supplied to drive the single-phase load. When the single-phase circuit 500 is a single-phase AC power supply via a reactor, the DC power of the DC power supply 100 is converted to AC power via the inverter 400 and regenerated to the single-phase AC power supply. On the other hand, between the inverter 400 and the DC power supply 100, the inverter 400 is caused to output a zero voltage vector to control the zero-phase voltage and the zero-phase current, thereby exchanging DC power. That is, the inverter 400 includes the single-phase circuit 50.
0 is exchanged with the DC power supply 100, and AC power is exchanged with the DC power supply 100 by time division. When the DC power is exchanged with the DC power supply 100, the inverter 400
Performs the action of a chopper that performs a DC-DC conversion operation. As a result, the DC-DC converter 200 as shown in FIG. 10 is no longer necessary, and the semiconductor switching elements and the drive circuits for the converter 200 that constitute the converter 200 can be reduced.

Each of the following inventions further embodies the single-phase circuit 500, the diode group 600, and the DC power supply 100 in the invention described in claim 1. First, the invention according to claim 2 is the single-phase circuit 5 according to the invention according to claim 1.
00 is a single-phase load. That is, the invention according to claim 2 is connected in series between the same single-phase voltage source inverter and smoothing capacitor, a single-phase load connected between the AC output terminals of the inverter, and the AC output terminal of the inverter, and , A diode group consisting of two diodes whose polarities are inverted in the middle of the mutual connection point, a reactor whose one end is connected to the polarity inversion point of this diode group, and the other end of this reactor and one end of the smoothing capacitor. And a DC power source connected between them. Then, by the switching operation of the inverter, the inverter transfers AC power to and from the single-phase load, and transfers DC power to and from the DC power supply via the diode group by the output of the zero voltage vector.

According to a third aspect of the invention, the single-phase circuit 500 in the first aspect of the invention is a single-phase AC power supply, and the power of the DC power supply is regenerated to the single-phase AC power supply by the operation of the inverter. . That is, the invention according to claim 3 is the same single-phase voltage source inverter and smoothing capacitor, a single-phase AC power source connected between the AC output terminals of the inverter via the first reactor, and the single-phase AC power source. A diode group consisting of two diodes connected in series between both terminals of the power source and having polarities inverted in the middle of their mutual connection points, and a second reactor having one end connected to the polarity inversion point of this diode group And a DC power supply connected between the other end of the second reactor and one end of the smoothing capacitor. Then, by the switching operation of the inverter, the inverter transfers AC power to and from the single-phase AC power supply to regenerate the power of the DC power supply, and at the time of outputting the zero voltage vector, the DC power is supplied via the diode group. DC power is exchanged between the two.

Further, the invention according to claim 4 is also one in which the single-phase circuit 500 in the invention of claim 1 is a single-phase AC power supply, and the power of the DC power supply is regenerated to the single-phase AC power supply by the operation of the inverter. Is. That is, the invention according to claim 4 has the same single-phase voltage source inverter and smoothing capacitor, the first reactor whose one end is connected to one AC output terminal of the inverter, and the other AC output terminal of the inverter. A second reactor having one end connected, a single-phase AC power supply connected between the other ends of the first and second reactors, and a series connection between both terminals of the single-phase AC power supply, and A diode group including two diodes whose polarities are inverted in the middle of mutual connection points, and a DC power supply connected between the polarity inversion point of the diode group and one end of the smoothing capacitor are provided. Then, by the switching operation of the inverter, the inverter transfers AC power to and from the single-phase AC power supply to regenerate the power of the DC power supply, and at the time of outputting the zero voltage vector, the DC power is supplied via the diode group. DC power is exchanged between the two.

Further, the invention according to claim 5 is the DC-AC power converter according to claim 2, 3 or 4, wherein the DC power supply is formed by combining an AC power supply and a rectifier circuit. .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 2 is a circuit diagram showing an embodiment of the invention described in claim 2. In the figure, 101 is a DC power source, 102 is a reactor, 301 is a smoothing capacitor, 401 is a single-phase voltage type inverter consisting of self-extinguishing type semiconductor switching elements Tr1 to Tr4 such as IGBTs and diodes antiparallel to each switching element. , 50
Reference numeral 1 is a single-phase load such as a single-phase AC motor connected to the AC output terminal of the inverter 401, and 601 is diodes D1 and D.
2 are connected in series with opposite polarities, and each diode D1,
The cathode of D2 is connected to the AC output terminal of the inverter 401, and the anode (which is the interconnection point of the diodes D1 and D2 and also the polarity reversal point) is connected to the reactor 10.
2 is a diode group connected to one end of 2. Here, the positive electrode of the DC power supply 101 is connected to the other end of the reactor 102, and the negative electrode is connected to the connection point between the lower arm of the inverter 401 and the smoothing capacitor 301.

In this embodiment, a single-phase voltage source inverter 40 is used.
It focuses on the zero voltage vector of 1. That is,
In order to output a zero voltage vector in the single-phase voltage source inverter 401, there are two switching patterns, that is, the case where all the upper arms are made conductive and the case where all the lower arms are made conductive, and this degree of freedom is utilized in this embodiment. .
Since the zero-phase voltage output from the inverter 401 does not appear in the line voltage, it does not affect the AC power supply to the single-phase load 501. Therefore, the equivalent circuit for the positive phase is as shown in FIG. 3, and the power supply to the single-phase load 501 operates as the same inverter as the conventional one, and controls the power by the line voltage of the inverter 401 and the current flowing between the lines. AC power is exchanged with the single-phase load 501. The voltage of the DC power supply 101 becomes a zero-phase voltage when viewed from the AC output terminal of the inverter 401 through the diodes D1 and D2 of the diode group 601, and the zero-phase current is bypassed by the diode group 601 by the above connection, and the single-phase load is applied. No flow to 501.

On the other hand, considering the zero-phase component, it becomes as shown in FIG. 4, and the two arms of the inverter 401 in FIG. 3 can be regarded as one arm 401 'which performs switching operation at the ratio of the zero voltage vector. That is, FIG.
The conventional boost chopper 201 shown in FIG. 1 can be substituted by controlling the zero-phase voltage by the inverter 401 in FIG. 601 'in FIG. 4 is a diode equivalently showing the diode group 601 in FIG.

Therefore, by outputting the zero voltage vector by the switching operation of the inverter 401,
The same operation as the step-up chopper 201 in FIG. 11 is possible, and DC power can be transferred between the DC power supply 101 and the capacitor 301. That is, since the circuit shown in FIG. 2 can realize a DC-AC power conversion device substantially similar to that of FIG. 11, the semiconductor switching elements constituting the step-up chopper can be reduced to simplify and miniaturize the circuit configuration. Therefore, the cost can be reduced.

The inverter 401 in FIG. 2 has a PWM control.
The PWM pulse is controlled by the control shown in FIG. 5, for example.
Created by the circuit. That is, in FIG.
Voltage command V_dc ^*And DC voltage detection value V_dcAddition of deviation from
701 and input to the voltage controller 702 for zero phase
(Input) current command i ₀ ^*To get In addition, this zero-phase current command
i₀ ^*And zero-phase current detection value i₀And the deviation from
Then, the deviation is input to the current controller 704. one
Output voltage command v of the inverter 401_out ^*Absolute value inspection
The absolute value is obtained by inputting it to the output device 706, and this absolute value is calculated.
Subtract from the output of the current controller 704 by the adder 709
Zero-phase voltage command v_o ^*To get Output voltage command v_out ^*And zero phase
Voltage command v_o ^*And are added by the adder 707, and
Output voltage command v in the sex reversing device 705_out ^*The polarity of
Signal and zero-phase voltage command v_o ^*And are added by the adder 708.
After the addition, these addition results are compared by the comparators 710, 7
Compared with the triangular wave by 11, the DC voltage detection value V_dcDirect current
Voltage command V_dc ^*Of the inverter 401
PWM pattern for the switching elements Tr1 to Tr4
Get

In this embodiment, the positive electrode of the DC power supply 101 is connected to the upper arm of the inverter 401 and the smoothing capacitor 30.
When connecting to the connection point with 1, the negative electrode of the DC power supply 101 is connected to one end of the reactor 102, and the other end is connected to the connection point (polarity inversion point) between the cathodes of the diodes D1 and D2. The anodes of the diodes D1 and D2 may be connected to the AC output terminals of the inverter 401, respectively.

FIG. 6 is a circuit diagram showing an embodiment of the invention described in claim 3. This embodiment corresponds to the conventional technique of FIG. 12 and is a case where the AC power output from the inverter 401 is regenerated to the single-phase AC power supply 502. The other components that are the same as those in the embodiment of FIG. 2 are denoted by the same reference numerals. In this embodiment, the control circuit shown in FIG. 7 is used to make the regenerative current waveform a sine wave. That is, the deviation between the regenerative current command i _r ^* and the actual regenerative current detection value i _r is obtained by the adder 712, and this deviation is input to the current controller 713 to obtain the output voltage command v _out ^* . The contents of the following control calculation are the same as in FIG.

The operation of this embodiment is almost the same as that of the embodiment of FIG. 2, and the operation of the step-up chopper 201 in FIG. Send and receive DC power. At this time, since the zero-phase current is bypassed by the diode group 601, it does not flow to the single-phase AC power supply 502 side. At the time of power regeneration, a sinusoidal current i _r is passed to regenerate the DC power of the DC power supply 101 to the single-phase AC power supply 502 via the inverter 401.

In this embodiment, the positive electrode of the DC power supply 101 is connected to the upper arm of the inverter 401 and the smoothing capacitor 30.
When connecting to the connection point with 1, the negative electrode of the DC power supply 101 is connected to one end of the reactor 102, and the other end is connected to the connection point (polarity inversion point) between the cathodes of the diodes D1 and D2. The anodes of the diodes D1 and D2 may be connected to both ends of the single-phase AC power source 502, respectively.

FIG. 8 is a circuit diagram showing an embodiment of the invention described in claim 4. In this embodiment, a first reactor 503 and a second reactor 504 are provided between the AC output terminal of the inverter 401 and both ends of the single-phase AC power supply 502.
Has been inserted. With this configuration, the current flowing through the reactors 503 and 504 can be smaller than that of the DC reactor 102 in the embodiment of FIG. 2 or FIG.
Reactor responsibilities are reduced. The control method is shown in FIG.
Alternatively, as in the embodiment of FIG. 6, it is necessary to detect the currents flowing through the reactors 503 and 504 in order to obtain the zero-phase current and the regenerative current commands and separate the positive-phase component and the zero-phase component.

In this embodiment, the positive electrode of the DC power supply 101 is connected to the upper arm of the inverter 401 and the smoothing capacitor 30.
When connecting to the connection point with 1, the negative electrode of the DC power supply 101 is connected to the connection point (polarity inversion point) of the cathodes of the diodes D1 and D2, and the anodes of the diodes D1 and D2 are connected to the single-phase AC power supply. It may be connected to both ends of 502.

FIG. 9 is a circuit diagram showing an embodiment of the invention described in claim 5. In this embodiment, instead of the DC power supply 101 in the embodiment of FIG.
Single-phase full-wave rectifier circuit 50 consisting of 2 and diode bridge
5 is used in combination. As the control circuit of this embodiment, by multiplying the output of the voltage controller 702 in FIG. 5 by the absolute value of the sine wave synchronized with the AC power supply voltage, it becomes possible to control the AC input current in a sine wave shape. Although not shown, a multi-phase AC power supply such as a three-phase power supply and a full-wave rectifier circuit may be combined and replaced with a DC power supply. The combination of the single-phase or multi-phase AC power supply of this embodiment and the rectifier circuit can be applied to the DC power supply 101 of the embodiments of FIGS. 6 and 8 other than FIG.

[0028]

As described above, according to the present invention, a DC-DC converter such as a step-up chopper for setting the DC voltage of a single-phase voltage source inverter to a predetermined value can be substituted by the inverter. Therefore, it is possible to reduce the semiconductor switching element, its drive circuit, drive power source, and the like in the entire device, and it is possible to simplify the circuit configuration, downsize the device, and reduce the cost.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of the invention described in claim 1.

FIG. 2 is a circuit diagram showing an embodiment of the invention described in claim 2.

3 is a positive-phase equivalent circuit of the embodiment of FIG.

4 is a zero-phase equivalent circuit of the embodiment of FIG.

5 is a control circuit diagram of the embodiment of FIG. 2. FIG.

FIG. 6 is a circuit diagram showing an embodiment of the invention described in claim 3.

FIG. 7 is a control circuit diagram of the embodiment of FIG.

FIG. 8 is a circuit diagram showing an embodiment of the invention described in claim 4.

FIG. 9 is a circuit diagram showing an embodiment of the invention described in claim 5.

FIG. 10 is a diagram conceptually showing a conventional technique.

FIG. 11 is a circuit diagram showing a conventional technique.

FIG. 12 is a circuit diagram showing a conventional technique.

[Explanation of symbols]

100, 101 DC power supply 102 Reactor 300, 301 Smoothing capacitor 400, 401 Single-phase voltage source inverter 401 'Arm 500 Single-phase circuit 501 Single-phase load 502 Single-phase AC power supply 503, 504 Reactor 600, 601 Diode group 601' Diode 701 703, 707, 708, 709, 712 Adder 702 Voltage controller 704, 713 Current controller 705 Polarity inverter 706 Absolute value detector 710, 711 Comparator Tr1-Tr4 Self-extinguishing type semiconductor switching element D1, D2 Diode

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02M 7/5387 H02M 1/08

Claims (5)

(57) [Claims] 1. A single-phase voltage source inverter for converting DC-AC power by operation of a semiconductor switching element to output a single-phase AC voltage, a smoothing capacitor connected between DC input terminals of the inverter, and an inverter. A single-phase circuit connected between the AC output terminals, a diode group consisting of a plurality of diodes connected in series between the AC output terminals of the inverter, and having their polarities inverted in the middle of their mutual connection points, and the inside of this diode group. And a DC power source connected between one end of the smoothing capacitor and the polarity reversal point, and by time division, the inverter exchanges AC power with the single-phase circuit and outputs a zero voltage vector. A DC-AC power conversion device, characterized in that DC power is exchanged with a DC power supply via a group of diodes at times. 2. A single-phase voltage source inverter for converting DC-AC power by operating a semiconductor switching element to output a single-phase AC voltage, a smoothing capacitor connected between DC input terminals of the inverter, and an inverter. A single-phase load connected between AC output terminals, a diode group consisting of two diodes connected in series between AC output terminals of the inverter, and having polarities inverted in the middle of mutual connection points, and this diode group The reactor has one end connected to the polarity reversal point and a DC power supply connected between the other end of this reactor and one end of the smoothing capacitor. AC power is transmitted and received at the same time, and DC power is transmitted and received between the DC power supply and the DC power supply through the diode group when the zero voltage vector is output. Power converter. 3. A single-phase voltage source inverter for converting DC-AC power by operation of a semiconductor switching element to output a single-phase AC voltage, a smoothing capacitor connected between DC input terminals of the inverter, and an inverter. A single-phase AC power supply connected between the AC output terminals via the first reactor and a series connection between both terminals of the single-phase AC power supply,
In addition, a diode group including two diodes whose polarities are inverted in the middle of the mutual connection points, a second reactor whose one end is connected to the polarity inversion point of this diode group, and a second reactor
Of the DC power supply connected between the other end of the reactor and the one end of the smoothing capacitor, and by time division, the inverter transfers AC power to and receives AC power from the single-phase AC power supply. A DC-AC power converter, which regenerates and transfers DC power to and from a DC power supply via a diode group when a zero voltage vector is output. 4. A single-phase voltage source inverter for converting DC-AC power by operation of a semiconductor switching element to output a single-phase AC voltage, a smoothing capacitor connected between DC input terminals of the inverter, and an inverter. A first reactor whose one end is connected to one AC output terminal, and a second reactor whose one end is connected to the other AC output terminal of the inverter
, A single-phase AC power supply connected between the other ends of these first and second reactors, and a series connection between both terminals of the single-phase AC power supply, and in the middle of mutual connection points. A diode group including two diodes whose polarities are inverted, and a DC power source connected between the polarity reversal point of this diode group and one end of the smoothing capacitor are provided, and the inverter is a single-phase AC DC-characterized in that AC power is transferred to and from the power supply to regenerate the power of the DC power supply, and DC power is transferred to and from the DC power supply via the diode group when the zero voltage vector is output. AC power converter. 5. The DC-AC power converter according to claim 2, 3 or 4, wherein the DC power supply is configured by combining an AC power supply and a rectifier circuit.